Thermal and mechanical properties of biodegradable composites with nanometric cellulose

Abstract

These days, biodegradable polymers, due to their biocompatibility and biodegradability, gain much interest. They have significantly contributed to the development of new materials that can be used in packaging industry, medicine, and agriculture. Particularly, composites made of biodegradable polymers and renewable fillers are of great interest. In this work, two polymorphic forms of cellulose, differing also in terms of particle sizes, were used as fillers for polylactide (PLA). Composites were prepared by solvent casting method and then subjected to numerous tests. Wide-angle X-ray scattering, differential scanning calorimetry, and optical microscopy techniques were applied to define supermolecular structure of functional PLA/cellulose composites, crystallization parameters, as well as to observe phase transitions. Moreover, mechanical tests were carried out to assess the effect of polymorphic forms of cellulose on mechanical properties of composite materials. Polarization microscopy studies revealed that only cellulose I exhibits an ability to generate transcrystalline structures in the PLA matrix. Results of mechanical tests and thermogravimetric analysis showed a significant influence of particle size and polymorphic structure of cellulose on the tensile properties and thermostability of composites.